package com.wc.AlgoOJ_train.train2_DP训练.c1.DP0001;

import java.util.Scanner;

/**
 * @Author congge
 * @Date 2024/1/11 22:18
 * @description 上台阶
 * http://43.138.190.70:8888/p/DP0001
 */
public class Main {
    public static void main(String[] args) {
        long[] dp = new long[50 + 1];
        dp[1] = 1;
        dp[0] = 1;
        for (int i = 2; i <= 50; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(dp[n]);
    }
}
